Thin primarily brick functions as an architectural wall covering that has the low maintenance benefits of conventional brick masonry. Secondarily, thin brick will provide some protection to the material over which it is applied.
Thin brick, as well as architectural mounting systems therefore, are well known. Typically, a mounting panel, which may be a painted or galvanized steel sheet, is affixed to a vertical wall of a building, for example, over an environmental barrier and exterior grade plywood. The known mounting panels have ledges for the supporting the bottom of the thin brick. In this case, bricks are retained in place with an adhesive, designed to hold the thin brick until mortar is applied and sets.
The Brick Institute of America has issued Technical Notes 28C, Thin Brick Veneer—Introduction [January 1986] (Reissued January 2001), available at www.bia.org/BIA/technotes/t28c.htm. Thin brick are generically known as thin fired clay units, which are employed as interior or exterior wall coverings. Thin brick veneer is used in commercial, residential and do-it-yourself markets. Thin brick units are typically formed from shale and/or clay, and are kiln-fired. These thin brick units are much like facing brick (ASTM C 216), except they are approximately ½ to 1 in. (12 to 25 mm) thick. The face sizes are normally the same as conventional brick and therefore, when in place, give the appearance of a conventional brick masonry wall. ASTM C 1088 Thin Veneer Brick Units made from Clay or Shale covers two grades for exposure conditions to weather which are defined as Exterior and Interior. The three types of thin veneer brick are based on appearance and are defined as TBS, TBX and TBA. Minimum compressive strengths are not required in C 1088 as there is no way to test thin brick in compression.
In the early 1950's, the Structural Clay Products Research Foundation (now the Brick Institute of America) began the development of “SCR Re-Nu-Veneer”, a ¾ in. (19 mm) thick fired clay unit which had Norman size nominal face dimensions (2⅔ in. by 12 in. [68 mm by 305 mm]). In addition to developing the thin units, the Foundation developed special clips to attach the units to an existing wall, mortar for grouting the joints and a power-driven grouting gun. Today, thin brick are being installed using a variety of procedures. In Japan and in the United States, thin brick have been placed into forms and cast integrally with concrete, thus providing a very attractive architectural precast concrete panel. Another procedure involves bonding thin brick to a 16 in. by 48 in. (406 mm by 1220 mm) substrate, resulting in small, lightweight, easily installed modular panels. Ceramic tile installation techniques are often used to install the brick units, either at the jobsite or on prefabricated panels, and homeowners are renovating with do-it-yourself thin brick products.
Thin brick are available in various sizes, colors and textures. The most commonly found face size is standard modular with nominal dimensions of 2⅔ in. by 8 in. (68 mm by 203 mm). The actual face dimensions vary slightly among manufacturers, but are typically ⅜ in. to ½ in. (10 mm to 13 mm) less than the nominal dimensions. The economy size unit is 50% longer and higher, with the same aspect ratio, with a face size of 4 in. by 12 in. (102 mm by 305 mm). Other sizes, such as Norwegian, 3-in. (76 mm), non-modular, oversize, etc., may be available.
There are several methods of thin brick installation. Adhered veneer relies on a bonding agent between the thin brick units and the backup substrate. Adhered veneer construction may be classified as either thin bed set or thick bed set. The thin bed set procedure typically utilizes an epoxy or organic adhesive, and is normally used on interior surfaces only. For areas subject to dampness, only clear and dry masonry surfaces or concrete surfaces should be used for backup. For dry locations, the backing material (substrate) may be wood, wallboard, masonry, etc. A cross-section depicting a wood frame wall upon which thin brick veneer (thin set procedure) is installed is shown in FIG. 1.
The thick bed set procedure is often used on interior and exterior surfaces. The backing material may be masonry, concrete, steel or wood stud framing. The thick bed setting procedure over concrete masonry is illustrated in FIG. 2. The wire lath shown in FIG. 2 may be eliminated if the masonry wall is heavily scarified (sand-blasted). (Williams, Griffith, Jr., “New Bricklike Tile Veneer”, Building Standards, July-August, 1982). For applications over steel studs, procedures are similar to those used for concrete or masonry backup; however, wallboard and building felt must be installed over the studs before the lath and mortar bed are placed. Thick bed setting of thin brick over steel studs is shown in FIG. 3.
Prefabrication, utilizing thin brick veneer units, has been accomplished using the “casting” method. This process involves the combination of thin brick, grout and/or concrete cast into a prefabricated panel (similar to architectural pre-cast concrete). This process requires the use of forms, a method of placing the units, and a system for grouting. The usual practice is to place the units face down into a form (or waffle mold), and place a very fluid grout over the back surface of the units. The grout flows into the space between the units, thus forming the appearance of mortar joints. Concrete and reinforcement are placed over the grout to provide structural support.
Modular panels are produced by several different companies and each system differs slightly. Basically, thin brick units are adhered to modular panels in the factory, or at the jobsite. The modular panels have dimensions of approximately 16 in. by 48 in. (406 mm by 1220 mm), as shown in FIG. 4. The backing materials to which the brick units are adhered may consist of polystyrene, polyurethane, cementitious board, asphalt-impregnated fiber board, plywood, aluminum, or a combination of these materials, depending on the manufacturer.
The panels weigh approximately 35 lb (16 Kg), which is light enough for one person to handle easily. Installation techniques vary only slightly among the different manufacturers. The head and bed joints between the thin brick units may be grouted after the panels are secured to the supporting wall.
Key-Lok Thin Brick Systems, Inc. produces a steel panel adapted for supporting thin brick. See, www.key-lok.com. The Key-Lok Thin Brick Siding is a mechanical support and spacing system that is based on an architectural grade galvanized steel pan specifically designed for the application of thin brick veneers. The Key-Lok support panels are 16″ inches high and 48″ inches in length. The Key-Lok thin brick system is a 4 component system, comprising a mechanical support and spacing system (the galvanized steel sheet), the brick, the mortar, and an adhesive to secure the brick to the steel sheet.
The Key-Lok system provides “brick keys” that, when encapsulated into the mortar, perform the function of seven to eight brick ties per brick. These keys are present at the lower edge of the thin brick as a support, and within the mortar on the upper edge. “Adhesive keys” allow the brick to “form mechanical adhesion to the metal rather than ‘stuck’ to the metal”. These are indentations or slots in the steel, behind the brick, which therefore provide an adhesion strength dependent on the tensile strength of the adhesive, and not the strength of the bond between the adhesive and the steel. Each brick unit or piece is supported by and spaced with a support key ledge that is designed into the steel pan. A mechanical lock for the mortar and adhesive is provided for adherence. When the mortar and adhesive keys into these locks, each brick is permanently locked to the metal panel.
The thin brick support system may be mounted on various substrates, such as Orientated Strand Board (OSB), Exterior Grade Plywood, Exterior Grade Gypsum Sheathing, Block, Brick, Concrete and other sound substrates. Sheathing substrates may require a secondary weather resistive barrier such as Tyvek™ environmental barrier. The Key-Lok metal support pan has horizontal stiffening channels which add rigidity, allow for mechanical attachment, and create a chamber behind the system for water drainage and airflow. The metal support pan is approximately 0.012 in thickness and is designed as an architectural acceptable and commercial grade product, galvanized to a G-90 rating.
In order to mount the steel support pan, for wood frame construction, corner panels are required, which are installed before the regular flat panels. A benchmark is determined, and all measurements aligned with the benchmark, to assure level course of brick. A gap of ⅛″ to ¼″ of provided for thermal expansion. The panel is installed flat and tight to the supporting substrate, using non-corrosive fasteners, such as self tapping galvanized screws for steel studs, #8 coated deck screws for wood studs, and Tapcons, powder actuated or air actuated gun fasteners for masonry. Each panel has a “starter ledge” that rests on the brick supports of the panel below. Vertical joints are typically staggered on adjacent columns. The fasteners are placed in the channels, at a rate of about one per square foot, with an 8″ vertical spacing (stud spacing horizontally) preferred on stud walls.
In order to mount the thin brick, adhesive is applied horizontally on the upper portion of the metal brick tracks along the adhesive locks. A ¼″ bead is applied, leaving 2 inch gaps every 12″ to 18″ for moisture drainage. In most cases, corner bricks are to be installed first. Measurements are made for layout and to assure fit and brick spacing. Brick joints can be adjusted ±⅛″, allowing a ¾″ adjustment along a 40 foot wall. The mortar lock keys support the bricks. To ensure adhesion, the brick is nestled into the adhesive, breaking any “skin” that may have developed. The Key-Lok Mortar is a premixed product that comes in a bag, and requires the addition of clean potable water only. A Grout bag (a.k.a. Pastry bag) with a #5 tip is used to install the mortar into the joint. The mortar joint is fully filled so the mortar will grab the mortar key locks incorporated into the pan. The grout is squeezed into the bed (horizontal) joints first, starting at the top of the wall, with continuous movement. The joints are over-filled. The head (vertical) joints are then filled. Care is exercised to avoid getting excess grout on the face of the brick, since this is cosmetically unattractive, and therefore requires removal. When the mortar joints have become firm, thumb print dry, they are then pointed up with a metal brick jointing tool. Excess mortar is raked out, and the edges around brick compacted and sealed. The mortar is then striked with a commercially available tool, to compress the mortar into the joint and remove excess.
Another thin brick mounting system is the EZ Wall® Panel System, from American Brick Company, Detroit Mich. The system includes the EZ Wall® galvanized panel, mastic glue, and mortar for the joint. Similar to the Key-Lok system, bricks are supported by tabs in the mortar space, and initially held to the panel with adhesive, although the panel itself is flat with perforations and tabs extending perpendicularly from the plane of the panel. The panel is formed of 29 gauge, zinc coated galvanized to G-90 Commercial Grade coating protection, in four foot square panel sizes. The Insulok® system, also from American Brick Company, is similar, providing continuous ledges for the thin brick. See, www.ambrico.com/products.htm.
U.S. Pat. Nos. 5,501,049 and 5,373,676 each discloses a thin brick mounting system in which individual brackets are provided for each brick, supporting the brick and the bottom, with a dovetail retainer of a relatively thick panel retaining the top edge.
U.S. Published Patent Application No. 2003/0213212 discloses a thin brick mounting system in which a dovetail retainer of a relatively thick panel retains both the top and bottom edge of the thin brick.
U.S. Published Patent Application 2003/0121225 and U.S. Pat. Nos. 5,311,714, 5,228,937, and 4,947,600 each provides a thin brick mounting system in which a ledge is formed for supporting the brick on a lower edge thereof.
U.S. Published Patent Application 2004/0050003 and U.S. Pat. Nos. 6,098,363 and 3,321,883 each disclose a thin brick mounting system in which a panel has a set of retaining tabs formed thereon, each retaining tab both supporting a thin brick above and locking a top edge of a grooved brick below.
U.S. Pat. Nos. 2,832,102 and 5,390,457 each discloses a support panel for a specially contoured brick or tile, providing an interlocking structure which reduces the amount of mortar employed.
U.S. Pat. No. 4,662,140 provides a masonry or brick support panel having a set of ledges for supporting the lower edge of the brick, with adhesive strips supported by tabs protruding from the sheet to retain the brick to the panel.
U.S. Pat. Nos. 6,164,029, 4,890,433, 4,856,246, 4,238,915, 2,082,241, and 2,022,363, and each provide a tile or slabstone mounting panel with protrusions extending from the rear of the panel into a deep recess or recesses in the rear of the tile. This recess is, for example one quarter, one half, or more, of the time thickness, and the angle of the support is, for example, about 45 degrees.
U.S. Pat. Nos. 5,379,561, 4,987,712, and 3,005,293 each discloses a bracket system for retaining a wall panel, at the top and bottom edges, through a groove formed in each.